Incoloy 825 vs Inconel 625 vs Inconel 600: Which Nickel Alloy Is Right for Your Application?
At FULLERKREG, we help engineers and procurement teams navigate the differences between nickel-based alloys that appear similar on the surface but perform very differently in service. Incoloy 825 (N08825), Inconel 625 (N06625), and Inconel 600 (N06600) are three of the most widely specified nickel alloys in chemical processing, oil & gas, and high-temperature industrial applications — but each has a distinct composition and performance profile.
This guide provides a direct technical comparison of all three grades, covering chemical composition and mechanical properties per their respective ASTM standards, so you can make an informed material selection decision.
Alloy Overview
- Incoloy 825 (N08825) — A nickel-iron-chromium alloy with additions of molybdenum, copper, and titanium. Outstanding resistance to both oxidizing and reducing corrosive environments, including sulfuric and phosphoric acids. Governed by ASTM B425.
- Inconel 625 (N06625) — A nickel-chromium-molybdenum alloy with niobium-tantalum additions for solid-solution strengthening. Exceptional strength, fabricability, and corrosion resistance from cryogenic temperatures to 980°C. Governed by ASTM B446.
- Inconel 600 (N06600) — A nickel-chromium alloy with high nickel content for resistance to oxidation, carburization, and chloride stress corrosion cracking. A general-purpose high-temperature alloy. Governed by ASTM B166.
Chemical Composition Comparison
All values are weight percent (%). Min = minimum required; Max = maximum allowed per respective ASTM standard.
Incoloy 825 — N08825 (ASTM B425)
| C | Mn | P | S | Si | Cr | Ni | Mo | Ti | Cu | Fe | Al | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Min | — | — | — | — | — | 19.5 | 38.0 | 2.5 | 0.6 | 1.50 | 22.0 | — |
| Max | 0.05 | 1.0 | 0.03 | 0.5 | 0.5 | 23.5 | 46.0 | 3.5 | 1.2 | 3.00 | — | 0.2 |
Inconel 625 — N06625 (ASTM B446)
| C | Mn | P | S | Si | Cr | Ni | Mo | Ti | Nb+Ta | Fe | Al | Co | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Min | — | — | — | — | — | 20.0 | 58.0 | 8.0 | — | 3.15 | — | — | — |
| Max | 0.10 | 0.5 | 0.015 | 0.015 | 0.5 | 23.0 | — | 10.0 | 0.4 | 4.15 | 5.0 | 0.4 | 1.0 |
Inconel 600 — N06600 (ASTM B166)
| C | Mn | S | Si | Cr | Ni | Cu | Fe | |
|---|---|---|---|---|---|---|---|---|
| Min | — | — | — | — | 14.0 | 72.0 | — | 6.0 |
| Max | 0.15 | 1.0 | 0.015 | 0.5 | 17.0 | — | 0.50 | 10.0 |
Mechanical Properties Comparison
| Grade | UNS | Standard | Tensile Strength Rm (N/mm²) min | Yield Strength Rp0.2 (N/mm²) min | Elongation A (%) min |
|---|---|---|---|---|---|
| Incoloy 825 | N08825 | ASTM B425 | ≥586 | ≥241 | ≥30 |
| Inconel 625 | N06625 | ASTM B446 | ≥827 | ≥414 | ≥30 |
| Inconel 600 | N06600 | ASTM B166 | ≥552 | ≥241 | ≥30 |
Key Differences at a Glance
| Parameter | Incoloy 825 (N08825) | Inconel 625 (N06625) | Inconel 600 (N06600) |
|---|---|---|---|
| Ni content (%) | 38.0–46.0 | ≥58.0 | ≥72.0 |
| Cr content (%) | 19.5–23.5 | 20.0–23.0 | 14.0–17.0 |
| Mo content (%) | 2.5–3.5 | 8.0–10.0 | — |
| Key alloying additions | Cu, Ti (corrosion) | Nb+Ta (strength) | High Ni (oxidation) |
| Tensile Strength min (N/mm²) | 586 | 827 | 552 |
| Yield Strength min (N/mm²) | 241 | 414 | 241 |
| Elongation min (%) | 30 | 30 | 30 |
| Primary strength mechanism | Solid solution | Solid solution + Nb precipitation | Solid solution |
| Key corrosion resistance | Sulfuric & phosphoric acids, seawater | Seawater, oxidizing & reducing acids | Oxidation, carburization, chloride SCC |
| Max service temperature | ~450°C (aqueous); ~980°C (oxidizing) | ~980°C | ~1175°C (oxidizing) |
| Governing ASTM standard | B425 (rod/bar) | B446 (rod/bar) | B166 (rod/bar) |
Application Selection Guide
Choose Incoloy 825 (N08825) when:
- Your environment involves sulfuric acid, phosphoric acid, or seawater at moderate temperatures
- Resistance to both oxidizing and reducing corrosion is required simultaneously
- Copper addition is beneficial for reducing acid resistance
- Typical applications: oil & gas downhole components, chemical process vessels, heat exchangers, pickling equipment, nuclear fuel reprocessing
Choose Inconel 625 (N06625) when:
- High mechanical strength is required alongside outstanding corrosion resistance
- Service spans a wide temperature range — from cryogenic to 980°C
- Resistance to pitting, crevice corrosion, and stress corrosion cracking in chloride environments is critical
- Typical applications: aerospace fasteners, marine hardware, chemical plant equipment, offshore risers, flue gas scrubbers, nuclear reactor components
Choose Inconel 600 (N06600) when:
- High-temperature oxidation and carburization resistance is the primary requirement
- Resistance to chloride-induced stress corrosion cracking is needed
- Service temperatures up to 1175°C in oxidizing atmospheres
- Typical applications: furnace components, heat treating equipment, chemical and food processing, nuclear engineering, electronic components
FULLERKREG Supply Capabilities
FULLERKREG supplies precision fasteners and engineered components in Incoloy 825, Inconel 625, and Inconel 600:
- Material Test Certificates (MTC) — EN 10204 3.1 / 3.2 available on request
- ASTM B425 / B446 / B166 compliance — rod and bar forms for fastener and structural applications
- Custom fastener dimensions — non-standard thread forms, head styles, and lengths
- Bulk wholesale pricing — OEM and MRO procurement with competitive lead times
- Global shipping — from our manufacturing base in China to customers worldwide
Need a quote or technical consultation for Incoloy 825, Inconel 625, or Inconel 600 fasteners? Contact FULLERKREG with your specification and our engineering team will respond promptly.
FULLERKREG — Precision Fasteners. Global Standards. Reliable Supply.